1. Field of the Invention
This invention relates to an ink jet recording method which performs recording on designated paper specially prepared for ink jet recording, and also on paper generally used in offices or homes such as copying paper, report paper, bond paper, continuous slip paper, etc., and various cloths with rapid fixing, with high optical density and little feathering.
2. Related Background Art
There have been made so many proposals about the ink jet recording method of the prior art, and in which the method for performing recording by use of a recording liquid (also called ink) containing a dye dissolved in water or a water-soluble organic solvent as main components has been the leading method.
In recording methods which use such ink, although the requisite items may differ slightly depending on the difference in individual system, the items commonly demanded which are particularly important are as follows:
(1) recorded images with good quality and high optical density without feathering should be obtained;
(2) fixing speed of ink should be rapid;
(3) durability of printed matter as regarding water resistance, lightfastness, etc., should be excellent;
(4) ink should not clog in the nozzle and in the ink passage way;
(5) stable ejection of ink should be obtained over a long term;
(6) no change of ink should occur even during long term storage, etc.
For satisfying some or all of the above objects, investigations have been aggressively made in both aspects of ink and device. However, even when ink jet printer systems which are commercially available are examined, there is no ink jet recording method yet which has satisfied the above objects sufficiently under the present circumstance. For example, when a minimally volatile polyalkylene glycol or glycerin for the prevention of clogging is added sufficiently to the mixture of a dye and water, the ink has poor penetration in normal paper with effective sizing because of the increased viscosity thereof, whereby several minutes may be required for fixing, thus posing a problem in practical application, although no clogging may occur.
For overcoming this problem, Unexamined Japanese Laid-Open Patent Publication No. 29546/1980 proposes to add a surfactant. In such a case, although improvement of fixing speed may be effected to a satisfactory extent depending on the kind or amount of the surfactant added, feathering becomes greater due to the lowering of the surface tension of the ink, whereby printing quality is lowered to great extent.
On the other hand, when a strongly basic substance is added in the ink as in Unexamined Japanese Patent Publication No. 57862/1981 in place of a surfactant, this substance destroys an internal sizing agent in the paper, typically rosin, and therefore fixing speed is rapid and printed letters with little feathering can be obtained. However, in the neutral paper, due to differences in the sizing agent, there is substantially no effect and of course the high pH substance is dangerous when used in the home or office.
Also, in Unexamined Japanese Patent Publication No. 49762/1983, there has been proposed the method in which recording is performed by defining the dynamic viscosity of ink from 4 to 8 cps at 35.degree. C., and maintaining the ink with a water content of 1/4 or less at 30.degree. C. or higher. According to this method, although satisfactory results can be obtained to some extent with respect to clogging and maintenance of stable high speed recording, problems will ensue particularly with respect to fixing characteristics and feathering on normal paper, because the solvents content in the ink is so high.